JPS5843055B2 - Process for producing coffee extract - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Countercurrent extraction of roasted and ground coffee is well known to those skilled in the art and is recognized as one of the most practical means for producing beverage products.

Countercurrent extraction is when the aqueous medium used to extract the coffee is first on-stream for an extended period of time.
m) contacting the coffee.

As this medium passes through the extraction zone, it continuously contacts the coffee and the coffee solubles content becomes higher and higher.

Immediately before draining from the brewing zone, it is passed through the freshest part of the coffee in operation.

Conventionally, countercurrent extraction is carried out through the use of an extraction zone having a plurality of separate percolators or extraction cells, usually three or more.

These cells or containers each hold partially extracted roasted and ground coffee and are connected such that the aqueous extraction medium passes through each in a consistent manner.

Extraction consists of a series of consecutive cycles.

Therefore, after a preselected operating period (this time depends on the weight of the extraction medium, i.e. the desired "draw-off"
w-off) Change the order of this cell after l passes through each cell.

The selection of the appropriate time and corresponding draw-off weight depends on the coffee extraction purpose.

This choice is then reflected in the "draw-off ratio," which is the weight of aqueous extract relative to the weight of coffee in the cell.

This ratio determines the yield and quality of the final beverage product.

Removal of cells containing mostly consumed or extracted coffee, i.e. cells at the end of the band where the aqueous extraction medium enters and new cells containing fresh, unextracted roasted and ground coffee at the other end of the band. Transfer is effected by substantially simultaneous additions.

Each such movement marks the end of a cycle and the beginning of the next cycle.

A disadvantage of this prior art countercurrent extraction is that the production of the extract is an intermittent cycle, regardless of the continuity of the extraction cycle.

A new cell added to the downstream end of the brewing zone is first filled with granulated roasted and ground coffee chisels.

Therefore, no extract will flow out of this zone until the cell is filled with extraction medium for the first time.

Therefore, at the beginning of each cycle there is a time delay in the flow of extract.

Also in accordance with prior art coffee beverage processing techniques, the extract exiting the extraction zone is typically first cooled to protect against heat-induced flavor deterioration and aroma loss, and then the yield is monitored and Measured to ensure the most efficient draw-off for each cycle.

Once determined by weighing, temporary stripping of the coffee extract volatiles, concentration of the stripped extract, reconstitution of the separated volatiles and extract and then subsequent It is usually transferred to further processing, including drying.

Since the t-IJ stripping of volatiles is carried out at high temperatures and most effectively on a continuous basis, further intermediate steps often occur between the measurement and stripping of the extract.

Therefore, in order to avoid sporadic stripping due to the fact that the extract is not continuously available from the extraction zone, this extract is usually introduced into a holding tank.

There, a sufficient amount of extract is retained to allow continuous and constant stripping.

Furthermore, since the extract is usually cooled immediately after leaving the extraction zone, it is usually reheated just before or during stripping.

°An object of the invention is also to produce a countercurrent extraction system that is completely continuous.

It is thus desirable to develop a process in which not only the extraction but also the flow of the extract is at a continuous rate.

It is also an object of the invention to reduce the number and time interval of holding and/or cooling steps between the discharge of the extract from the extraction zone and the removal of the volatiles from the extract by stripping.

Another object of the invention is the production of beverage materials having enhanced flavor and aroma to yield a more desirable beverage product.

These objects and additional advantages described below are obtained through the present invention.

The present invention is based on the discovery of the advantages resulting from the pretreatment of freshly roasted and ground coffee before its addition to the countercurrent extraction zone.

More particularly, this fresh coffee, usually held within a container or cell, is moistened with an aqueous coffee preparation.

Only the coffee after this pretreatment is added to the extraction zone and the extraction medium is passed therethrough.

"Brew" means an aqueous solution containing at least the non-volatile beverage solubles of coffee.

Additionally, the solution may contain coffee volatiles.

Thus, as used herein, the term "infusion" includes aqueous coffee extract, either stripped or unstripped of its normal volatile contents.

These extracts are further characterized as usually having a soluble solids content of 10 to 30%, preferably 12 to 18% of the total weight.

Furthermore, like the extraction medium itself, this leachate is desirably at a temperature of at least 80°C.

The coffee within the cell is in granular form.

This cell therefore has a significant void volume.

To fully utilize the invention, a pre-brewing process of fresh coffee is carried out with aqueous coffee infusion by filling this cellular void with infusion.

Furthermore, some of this infusion appears to be physically absorbed into the dried coffee.

Conventional grinding of coffee suitable for extraction typically allows about 2 to 3 kg of infusion liquid to be charged into the cells per kg of fresh coffee.

Up to 10% more infusion than what the cell retains is typically utilized to fill a new coffee cell.

This excess leachate overflows the cell and can be easily recycled for further processing.

However, overflow is desirable because it ensures that no void volume is left within the cell.

If the cell is not completely filled, there will be a gap in the flow of extract after the addition of the cell to the extraction zone.

Another advantage of the invention lies in the increased period of time during which new coffee cells are brewed.

Thus, in the prior art where a new cell of dry coffee is used, approximately 50% of the initial working stream is typically consumed in filling the cell and wetting the coffee in the brewing zone.

However, the extraction zone is prefilled.
) Extraction occurs throughout the cycle by adding cells.

The efficiency of extraction is thus increased.

Furthermore, since the prefilling takes place outside the extraction zone and preferably during the entire cycle time, the flow rate of the aqueous medium into the cell does not need to be as great as the cell is filled into the extraction zone.

This reduced filling rate allows a slower, more controlled diffusion of the aqueous medium through the dry fresh coffee.

This is called channeling to the cell.
) and further ensure complete liquid-solid contact for optimal extraction.

In addition to the processing advantages that prefilling of the new cell of roasted and ground coffee provides over prior art discontinuous techniques, it has been discovered that this prefilling further improves the quality of the final beverage product.

One way in which the final product is improved involves allowing greater draw-off from the freshly added cell with fresh coffee without the drawbacks normally associated with operating at high draw-off ratios.

Greater draw-off produces more desirable beverage flavors and aromas.

However, increasing draw-off has traditionally required an increase in the total volume of extraction media.

Therefore, the resulting draw-off was usually less concentrated and excess water had to be removed to raise the extract concentration sufficiently for optimal drying.

Furthermore, these draw-offs were limited by quality considerations since flavor loss during concentration is usually proportional to the weight of water removed.

However, according to the invention this draw-off is not increased by extra extraction medium, but rather through the portion of coffee infusion used to prefill the new cell before its addition to the extraction zone.

Thus, whereas conventional draw-off ratios typically range from about 2.0 to 3.5:1 based on extract to roasted coffee in a new cell, the present invention provides a draw-off ratio of 4.0 to 6.5:1. 5:1, most preferably 5.0 to 6.0.

Thus, the present invention avoids dilution of the final product, but allows for greater draw-off and associated improvements in infusion-like flavor.

Another flavor advantage of the present invention is the increased time that coffee is brewed.

Thus, since the cell is prefilled prior to addition to the brewing zone, the time during and after filling increases the time for volatiles and other coffee materials to dissolve.

This improvement is particularly noticeable with volatiles since they are often not easily solubilized.

The solubilization of volatiles is enhanced, especially when fresh coffee is contacted with a brewing liquid containing stripped extract.

Contact with the stripped extract creates conditions where the greatest difference in volatile content is found between the fresh coffee and the aqueous medium.

This results in a faster and more efficient transfer of volatiles to the extraction medium.

In yet another embodiment of the invention, these benefits can be increased by increasing the time that a new cell of coffee contains pre-filled infusion liquid.

This increase is obtained by keeping the cell prefilled with leachate for a period of time before it is added to the extraction zone.

This is done by wetting the coffee and promoting the transfer of roasted coffee flavor and aroma components to the infusion solution.

Thus, for example, a new cell of fresh coffee may be prefilled one cycle prior to addition to the zone, held in the prefilled state for a complete cycle or a partial cycle, and then added to the brewing zone.

The method by which the leachate is added to the new cell may be that conventionally used for the flow of aqueous media in the extraction zone.

It is thus passed upwardly through the coffee cell, entering at the bottom and exiting at the top.

This upward flow of liquid at a reduced rate through the coffee granules helps minimize backing and channeling within the cells, thus increasing the homogeneity of liquid-solid contact.

Additionally, this minimizes pressure on the screen or other porous retaining wall normally used to keep the coffee granules within the cell.

However, according to another embodiment of the invention, the cell is prefilled with the leachate by a two-stage seafence comprising first adding the leachate to the cell from its top and then completing the filling from the bottom of the cell. .

More specifically, about 10 to 50% of the volume of leachate required to fill the cell is added from the top, followed by the remainder from the bottom.

This top feed creates a bed of coffee that thoroughly wets the coffee and reduces its tendency to channeling, aiding filtration.

Also, as the infusion liquid begins to flow out of the cell (through the overflow filling or by passing the extraction medium after addition of the cell to the extraction zone), the surface particles of coffee are already completely wetted.

In this state, these surface particles are not easily carried away by the liquid present.

The number of coffee solid particles lost from the cell is therefore reduced.

Once the cell is completely filled with coffee infusion, it is ready to be added to the brewing zone and a new brewing cycle begins.

However, noticeably, this cell contains substantially no interstitial void volume, which volume is occupied by pre-filled leachate.

Thus, compared to the prior art, as soon as the cell is put into operation in the extraction zone, the force generated by the extraction medium entering the cell forces out the infusion liquid so as to maintain a continuous flow of aqueous coffee extract.

If the cell is not prefilled according to the invention,
A conventional periodic and intermittent outflow of extract occurs.

The aqueous extraction medium must first fill the void volume before it flows out of the extraction zone.

The coffee extract flowing out of the extraction zone at a constant rate is further processed according to one of the two embodiments of the invention.

In the simplest of these embodiments, this extract is divided.

A portion is redirected as a brewing liquid to pre-fill another cell with freshly roasted and ground coffee.
), while the rest is sent to the next processing stage, such as stripping.

In another and more preferred embodiment, all the extracts are stripped and the stripped extract is then divided such that an appropriate portion thereof is prefilled into a new cell containing fresh coffee. fixed, while the rest are further processed.

This division of the stripped or unstripped extract is usually carried out continuously through each draw-off.

Thus, a certain portion of the extract stream is redirected to prefill new, out-of-service cells with fresh coffee, while the remainder passes continuously to the next process.

In this method, leachate for prefilling is obtained without any reversal or change in flow rate in any part of the process system.

In both of these two embodiments, the intermediate prior art steps of extraction and stripping can be omitted.

It is primarily because of this simplification that the extract is drawn continuously from the extraction zone without interruption between cycles.

Stripping is thus carried out in a completely continuous manner without the need for intermediate holding tanks to ensure a continuous feed of extract for the stripping column.

A substantial conservation of energy also results, insofar as it is no longer necessary to first cool the extract for retention and reheat it for stripping.

The extract is passed substantially directly from the extraction zone where high temperatures are desired and to the stripper where high temperatures are desired.

Since the time required for the extract to undergo this transfer is greatly reduced, the need for care to ensure the stability of the extract relative to flavor components is greatly reduced.

As the extract is directed from at least one point in the extract flow system to the extraction zone, it is desirable to monitor extract yield following this point.

Furthermore, because of the continuous production of the extract here, it is expedient and practicable to postpone the monitoring from the intermediate point between the extraction and the stripping zone, which is customary in the prior art.

It is therefore preferred that the direction of the leachate for prefilling be monitored in terms of straight downward flow and, more preferably, that the extract yield be monitored by weighing the stripped extract just before its concentration.

During the passage of the aqueous extract to the stripper, sensitive coffee volatiles are removed and separated.

This separation is performed by prior art methods.

For example, steam is passed through the hot extract in a stripper to volatilize these flavor components.

Thereafter, the separated vapor and volatiles are concentrated and cooled to protect against flavor deterioration until the return of the volatiles to the further processed extract.

After stripping, the extract is usually concentrated.

This step is also carried out by means well known to those skilled in the art.

Thus, for example, heat and vacuum may be applied to it to evaporate excess water and increase its concentration for transport or subsequent drying.

Usually about 30-65% by total weight, preferably 45-6%
The concentrated extract having a soluble solids content of 0% is recombined with the previously separated volatiles to form a concentrated extract having volatiles and other solubles in substantially the proportions of a conventional beverage.

Concentrated extracts are sold that are diluted or reconstituted with water for drinking purposes.

However, preferably after mixing with the volatiles, the resulting extract is dried to yield a powdered beverage product.

This drying is also performed by conventional techniques.

Thus, for example, the reconstituted extract can be spray dried.

However, preferably the extract is lyophilized, as this technique ensures maximum retention of full flavor and aroma.

However, in yet another embodiment, the concentrated extract is dried prior to separation and reconstitution.

In this embodiment, volatiles are added to the powdered beverage product resulting from drying.

Thus, for example, concentrated volatiles can simply be sprayed onto a dried powder.

If desired, the atomized powder is then dried for a very short period of time sufficient to remove excess liquid.

This continuous nature and composition of the extract of the present application allows for certain further advantages according to the present invention.

Furthermore, the coffee extract draw-off is heterogeneous and remains of open average quality for some time during the brewing cycle, especially since the practice of the present invention does not require a holding tank between the brewing zone and the stripping zone.

The composition of the extract is thus dependent on the stage of draw-off to which it belongs or the point of draw-off in the cycle.

For example, the extract leaving the extraction zone early in a given cycle exhibits a higher concentration of coffee solubles and coffee aroma than the extract or draw-off late in the cycle.

These differences in concentration result from the fact that earlier in the cycle, the roasted and ground coffee contacted by the brewing stream is not extracted as much as later in the same cycle.

However, at the end of the cycle, the coffee contained in the last cell of the brewing zone has been at least partially extracted by the previous draw-off or previous stage of the draw-off cycle.

As a result, the content of coffee solubles and aromas is low;
And this reflects the decrease in these concentrations at the end stage of draw-off.

Of course, this decline in extractive concentration of beverage ingredients within each cycle is not new.

This is an inherent effect of the collapse extraction method.

However, it has not been thought that it is possible to substantially utilize this concentration difference.

Thus, because prior art treatment systems required the use of one or more holding tanks between the extraction zone and the subsequent treatment, this concentration difference could be reduced as the different stages of draw-off were mixed in the holding tanks. It disappeared before.

However, the method of the invention allows complete continuous processing of at least most of the extract without retention.

It is therefore possible to selectively process extracts at different stages.

This selection then allows the final product to have maximum flavor retention.

Accordingly, another embodiment of the invention provides up to about 70%, preferably 30%, of the direct extract through the entire treatment sea fence.
60% of the first stage.

The extract at this stage is thus passed directly from the extraction zone to a stripper, then concentrated and optionally dried.

Only the second or last stage extract, or as in this case the st-IJ-tubed extract, is redirected to prefill the new cells with fresh roasted and ground coffee.

Of course, not all of this last stage draw-off need be utilized to prefill new cells.

This last stage is itself successively divided as described above, with some being fixed and the remainder being sent to the next processing stage.

In accordance with this embodiment, the intermittent and selective redirection of the extract provides some variation in the flow rate of the extract throughout the portion of the method of the invention.

It is therefore desirable to insert a holding tank into the flow pattern after the point where the leachate is redirected.

If desired, the holding tank may also be inserted into the new cell prior to loading the new coffee.

However, even when a holding tank is required,
The flow of extract is normally only varied and not interrupted as in prior art systems.

Also, the tank is significantly smaller and the residence time is substantially limited.

The small drawbacks of these variations in flow are more than compensated for by increased process efficiency and superiority of the final beverage product.

Accordingly, selective redirection of draw-off of the late stage or part of the late stage due to prefilling constitutes a particularly preferred embodiment of the invention.

As mentioned above, the concentration of volatiles during the draw-off also changes, and this concentration decreases in the later stages of the draw-off.

It is also desirable to take advantage of this aspect of the invention.

Therefore, extract stripping is monitored within each cycle so that only the first stage of aroma stripped from each draw-off is used.

This initially stripped isolate is substantially higher in volatile concentration than subsequent isolates stripped from later stages.

For example, in steam stripping, the isolate obtained during the first stage of each draw-off exhibits a concentration of volatiles in the concentrated steam that is two to three times or more than that obtained in the later stages of the draw-off.

Selective use of only the initially stripped isolate of each draw-off is suitable for reconstitution of the final beverage material.

Thus, for example, these isolates may initially contain up to 70%, preferably 30 to 60%, for each draw-off.
Contains stripped volatiles.

These isolates exhibit substantially higher volatile concentrations than those obtained with the prior art.

Reconstitution therefrom with the initially stripped isolate minimized the dilution factor upon addition of the isolate to the beverage material.

In other embodiments, stripping is performed at higher speeds than conventionally, eg, using additional steam.

This provides improved yield and volatile spectrum.

Moreover, the separates, ie volatiles and concentrated vapors, are recovered only from the first portion of each draw-off, the total volume of which is not increased.

As a result, this isolate is added directly to the concentrated extract to provide the desired flavor without undue dilution.

The following examples further illustrate the invention.

Example 1 Roasted and ground coffee was extracted with water in a countercurrent extraction zone with six connected cells containing coffee.

6.0.1. Extraction was performed at a draw-off ratio of After exiting the extraction zone, the extract flow is divided into 60% and 40% by total weight.
Continuously divided into two parts.

This 40% portion was directed to a new off-stream cell containing fresh roasted and ground coffee.

This completely filled the interstitial voids of the cell and moistened the coffee over one cycle time where it was added gradually.

The remaining 60% of the effluent from the extraction zone was sent to a steam slumping column where it was stripped of volatiles, concentrated and separated.

The stripped extract, with a soluble solids content of 17% by weight, was then subjected to vacuum evaporation to yield a concentrated extract with a solids content of 60% by weight.

This concentrated extract was then reconstituted with the concentrate of volatiles removed in a stripping column, frozen and lyophilized to yield an instant coffee powder with a water content of approximately 3% by weight.

The extraction continued in a countercurrent extraction zone simultaneously with the processing of the first, 60% portion of the extract.

After the completion of each cycle, a new cell of fresh coffee filled with infusion during this cycle was connected to the downstream end of the brewing zone while the mostly extracted cells in the brewing zone were removed.

As each cycle began, a 40% portion of the divided extract was diverted to yet another cell containing fresh roasted and ground coffee to allow continuous operation of the process.

Significantly, the outflow of aqueous coffee extract from the brewing zone continued at a constant rate during the brewing cycle without being interrupted by exchange.

Example 2 All the aqueous extract leaving the extraction zone was sent directly to the stripper and then 60% of the stripped extract was
The process of Example 1 was repeated with the modification in portions of 40% to 40% by weight.

In the process of this example, a new cell containing freshly roasted and ground coffee was prefilled with infusion containing the stripped extract.

Again, the flow rate of extract through the process set-up did not change at the point of collapse following the cycle of extraction.

Example 3 The process of Example 2 was repeated with the modification that sl-IJ stubbed volatiles were recovered from the first 50% of the draw-off of each cycle.

Without concentration, this volatile isolate was used to reconstitute the extraction preparation until dryness.

The technique used to split the strip extract was also modified to obtain a portion for recycling.

Instead of continuously dividing the extract over the entire drawoff in a 60:40% ratio, all of the first 50% of the drawoff of each cycle was sent directly to concentration and subsequent processing.

75 vs. 25 only 50% after each cycle drawoff
Continuously divided in the ratio of %.

The portion after 25% draw-off was concentrated and sent directly to further processing.

This 75% portion was redirected to prefill a new cell with fresh roasted and ground coffee.

To allow prefilling of new cells at low feed rates, the process of this example included the retention of two new cells of roasted and ground coffee.

Therefore, one of the cells was filled for a fixed period of time, which is normal for a complete cycle, but since filling started in the middle of one cycle, this was extended to the middle of the next cycle.

Regarding the effectiveness of the second fresh cell, which was previously filled and kept in the filled state for half a cycle, a fresh cell of fresh roasted and ground coffee was used for addition to the brewing zone at the beginning of each cycle.

Example 4 The process of Example 1 was repeated.

However, instead of simply prefilling each folded cell containing freshly roasted and ground coffee from the bottom upwards, the first 25% of the redirected extract was added to the cells from the top.

Thereafter, the remaining 75% of the straightened extract (30% of the total extract leaves the extraction zone) was fed into the cell from the bottom to complete the prefill.

The extract monitored immediately prior to stripping was observed to contain substantially less entrained granular coffee solids than the corresponding extract of Example 1.

This desirable reduction in particulate content was due to the lower tendency of most of the top-filling coffee in the downflow cells in the extraction zone to be driven out of the cells by the effluent extraction medium.

Claims (1)

Claims: 1. A coffee extract is obtained by passing an aqueous medium in countercurrent through an extraction zone containing at least three connected cells containing roasted and ground coffee, the cells of this extraction zone being continuously During the brewing cycle, the coffee-containing end cell that is almost used up is removed, and a new coffee-containing cell is added to the opposite end to effect extraction of the brew; A method for producing a coffee extract, characterized in that the cell containing fresh coffee is filled with an aqueous coffee infusion before adding the cell to the extraction zone, whereby the extract flows continuously from the extraction zone. Manufacturing method. 2 Approximately 10 to 5 minutes of coffee aqueous infusion to fill the cell
2. The method of claim 1, wherein 0% is added to the top of the cell and the remainder of the aqueous infusion is then introduced into the cell from the bottom. 3. The method according to claim 1 or 2, wherein the aqueous coffee infusion liquid charged into the cell containing fresh coffee comprises coffee extract. 4. The method of claim 3, wherein the cells containing fresh coffee are filled at a substantially constant rate during one complete brewing cycle. 5. The method of claim 4, wherein the cell is filled, held in the filled state for at least a portion of the cycle, and then added to the extraction zone. 6. Claims comprising a brewing liquid in which the brew produced in the brewing zone is divided into two parts, the first part containing beverage material, and the second part introducing and filling a cell containing fresh coffee. The method according to item 3, item 4, or item 5. 7. The method according to claim 6, wherein the first and second portions are successively divided from the total extract. 8. The method of claim 6, wherein the second portion containing the infusion solution is separated from the extraction solution only after 70% of the draw-off of each cycle has been obtained. 9. Transferring the first portion to a stripping zone for separation of coffee volatiles, concentrating the resulting strip extract, mixing the separated coffee volatiles, and drying the mixture. the method of. 10. The separated coffee volatiles mixed with the first portion of the extract after the draw-off cycle consist of the extracted volatiles from the first 70% of the extract of the draw-off cycle. the method of. 11. A method according to any one of claims 1 to 10, wherein the infusion liquid filling the cells containing fresh coffee comprises coffee extract substantially stripped of coffee volatiles.